We can say that strawberries and lemons are the world's healthiest foods. Both these fruits contain a low amount of sugar that is helpful, as our body needs a certain amount of sugar. A lemon contains 70% sugar and a strawberry contain only 40% of sugar.
The reason that the lemon tastes sour even having more sugar than the strawberry is that the lemon contains a high amount of citric acid, usually 3% to 6%, that dominated the sweet taste of the lemon and results in the sour taste. The strawberry has less sugar than lemon but there is no acid content present in the strawberry, and therefore it tastes sweet.
People may think that a high amount of sugar in lemon may cause obesity, but lemon has many medicinal properties. Also, strawberries contain a high amount of carbohydrates in the form of starch, but it also has many health benefits.
If we keep aside a low amount of sugar that is present in both the fruits and just evaluate their nutritive values, we will find that the health benefits that they provide are much more than the amount of sugar present in them.